mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-13 14:50:17 +00:00
be9240c84c
After73fc4e28b9
, __libc_enable_secure_decided is always 0 and a statically linked executable may overwrite __libc_enable_secure without considering AT_SECURE. The __libc_enable_secure has been correctly initialized in _dl_aux_init, so just remove __libc_enable_secure_decided and __libc_init_secure. This allows us to remove some startup_get*id functions from22b79ed7f4
. Reviewed-by: Florian Weimer <fweimer@redhat.com> (cherry picked from commit3e9acce8c5
)
424 lines
13 KiB
C
424 lines
13 KiB
C
/* Perform initialization and invoke main.
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Copyright (C) 1998-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Note: This code is only part of the startup code proper for
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statically linked binaries. For dynamically linked binaries, it
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resides in libc.so. */
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/* Mark symbols hidden in static PIE for early self relocation to work. */
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#if BUILD_PIE_DEFAULT
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# pragma GCC visibility push(hidden)
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#endif
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#include <assert.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <libc-diag.h>
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#include <libc-internal.h>
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#include <elf/libc-early-init.h>
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#include <stdbool.h>
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#include <elf-initfini.h>
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#include <shlib-compat.h>
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#include <elf/dl-tunables.h>
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extern void __libc_init_first (int argc, char **argv, char **envp);
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#include <tls.h>
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#ifndef SHARED
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# include <dl-osinfo.h>
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# ifndef THREAD_SET_STACK_GUARD
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/* Only exported for architectures that don't store the stack guard canary
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in thread local area. */
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uintptr_t __stack_chk_guard attribute_relro;
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# endif
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# ifndef THREAD_SET_POINTER_GUARD
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/* Only exported for architectures that don't store the pointer guard
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value in thread local area. */
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uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
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# endif
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#endif
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#ifndef SHARED
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# include <link.h>
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# include <dl-irel.h>
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# ifdef ELF_MACHINE_IRELA
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# define IREL_T ElfW(Rela)
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# define IPLT_START __rela_iplt_start
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# define IPLT_END __rela_iplt_end
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# define IREL elf_irela
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# elif defined ELF_MACHINE_IREL
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# define IREL_T ElfW(Rel)
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# define IPLT_START __rel_iplt_start
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# define IPLT_END __rel_iplt_end
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# define IREL elf_irel
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# endif
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static void
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apply_irel (void)
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{
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# ifdef IREL
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/* We use weak references for these so that we'll still work with a linker
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that doesn't define them. Such a linker doesn't support IFUNC at all
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and so uses won't work, but a statically-linked program that doesn't
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use any IFUNC symbols won't have a problem. */
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extern const IREL_T IPLT_START[] __attribute__ ((weak));
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extern const IREL_T IPLT_END[] __attribute__ ((weak));
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for (const IREL_T *ipltent = IPLT_START; ipltent < IPLT_END; ++ipltent)
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IREL (ipltent);
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# endif
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}
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#endif
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#ifdef LIBC_START_MAIN
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# ifdef LIBC_START_DISABLE_INLINE
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# define STATIC static
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# else
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# define STATIC static inline __attribute__ ((always_inline))
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# endif
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# define DO_DEFINE_LIBC_START_MAIN_VERSION 0
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#else
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# define STATIC
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# define LIBC_START_MAIN __libc_start_main_impl
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# define DO_DEFINE_LIBC_START_MAIN_VERSION 1
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#endif
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#ifdef MAIN_AUXVEC_ARG
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/* main gets passed a pointer to the auxiliary. */
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# define MAIN_AUXVEC_DECL , void *
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# define MAIN_AUXVEC_PARAM , auxvec
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#else
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# define MAIN_AUXVEC_DECL
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# define MAIN_AUXVEC_PARAM
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#endif
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#ifndef ARCH_INIT_CPU_FEATURES
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# define ARCH_INIT_CPU_FEATURES()
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#endif
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/* Obtain the definition of __libc_start_call_main. */
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#include <libc_start_call_main.h>
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#ifdef SHARED
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/* Initialization for dynamic executables. Find the main executable
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link map and run its init functions. */
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static void
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call_init (int argc, char **argv, char **env)
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{
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/* Obtain the main map of the executable. */
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struct link_map *l = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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/* DT_PREINIT_ARRAY is not processed here. It is already handled in
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_dl_init in elf/dl-init.c. Also see the call_init function in
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the same file. */
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if (ELF_INITFINI && l->l_info[DT_INIT] != NULL)
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DL_CALL_DT_INIT(l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr,
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argc, argv, env);
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ElfW(Dyn) *init_array = l->l_info[DT_INIT_ARRAY];
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if (init_array != NULL)
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{
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unsigned int jm
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= l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
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ElfW(Addr) *addrs = (void *) (init_array->d_un.d_ptr + l->l_addr);
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for (unsigned int j = 0; j < jm; ++j)
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((dl_init_t) addrs[j]) (argc, argv, env);
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}
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}
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#else /* !SHARED */
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/* These magic symbols are provided by the linker. */
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extern void (*__preinit_array_start []) (int, char **, char **)
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attribute_hidden;
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extern void (*__preinit_array_end []) (int, char **, char **)
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attribute_hidden;
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extern void (*__init_array_start []) (int, char **, char **)
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attribute_hidden;
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extern void (*__init_array_end []) (int, char **, char **)
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attribute_hidden;
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extern void (*__fini_array_start []) (void) attribute_hidden;
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extern void (*__fini_array_end []) (void) attribute_hidden;
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# if ELF_INITFINI
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/* These function symbols are provided for the .init/.fini section entry
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points automagically by the linker. */
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extern void _init (void);
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extern void _fini (void);
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# endif
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/* Initialization for static executables. There is no dynamic
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segment, so we access the symbols directly. */
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static void
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call_init (int argc, char **argv, char **envp)
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{
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/* For static executables, preinit happens right before init. */
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{
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const size_t size = __preinit_array_end - __preinit_array_start;
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size_t i;
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for (i = 0; i < size; i++)
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(*__preinit_array_start [i]) (argc, argv, envp);
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}
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# if ELF_INITFINI
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_init ();
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# endif
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const size_t size = __init_array_end - __init_array_start;
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for (size_t i = 0; i < size; i++)
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(*__init_array_start [i]) (argc, argv, envp);
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}
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/* Likewise for the destructor. */
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static void
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call_fini (void *unused)
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{
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size_t i = __fini_array_end - __fini_array_start;
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while (i-- > 0)
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(*__fini_array_start [i]) ();
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# if ELF_INITFINI
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_fini ();
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# endif
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}
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#endif /* !SHARED */
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#include <libc-start.h>
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STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
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MAIN_AUXVEC_DECL),
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int argc,
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char **argv,
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#ifdef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec,
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#endif
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__typeof (main) init,
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void (*fini) (void),
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void (*rtld_fini) (void),
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void *stack_end)
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__attribute__ ((noreturn));
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/* Note: The init and fini parameters are no longer used. fini is
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completely unused, init is still called if not NULL, but the
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current startup code always passes NULL. (In the future, it would
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be possible to use fini to pass a version code if init is NULL, to
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indicate the link-time glibc without introducing a hard
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incompatibility for new programs with older glibc versions.)
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For dynamically linked executables, the dynamic segment is used to
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locate constructors and destructors. For statically linked
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executables, the relevant symbols are access directly. */
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STATIC int
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LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
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int argc, char **argv,
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#ifdef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec,
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#endif
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__typeof (main) init,
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void (*fini) (void),
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void (*rtld_fini) (void), void *stack_end)
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{
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#ifndef SHARED
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char **ev = &argv[argc + 1];
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__environ = ev;
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/* Store the lowest stack address. This is done in ld.so if this is
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the code for the DSO. */
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__libc_stack_end = stack_end;
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# ifdef HAVE_AUX_VECTOR
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/* First process the auxiliary vector since we need to find the
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program header to locate an eventually present PT_TLS entry. */
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# ifndef LIBC_START_MAIN_AUXVEC_ARG
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ElfW(auxv_t) *auxvec;
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{
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char **evp = ev;
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while (*evp++ != NULL)
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;
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auxvec = (ElfW(auxv_t) *) evp;
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}
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# endif
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_dl_aux_init (auxvec);
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if (GL(dl_phdr) == NULL)
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# endif
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{
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/* Starting from binutils-2.23, the linker will define the
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magic symbol __ehdr_start to point to our own ELF header
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if it is visible in a segment that also includes the phdrs.
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So we can set up _dl_phdr and _dl_phnum even without any
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information from auxv. */
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extern const ElfW(Ehdr) __ehdr_start
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# if BUILD_PIE_DEFAULT
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__attribute__ ((visibility ("hidden")));
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# else
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__attribute__ ((weak, visibility ("hidden")));
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if (&__ehdr_start != NULL)
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# endif
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{
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assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
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GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
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GL(dl_phnum) = __ehdr_start.e_phnum;
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}
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}
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__tunables_init (__environ);
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ARCH_INIT_CPU_FEATURES ();
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/* Do static pie self relocation after tunables and cpu features
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are setup for ifunc resolvers. Before this point relocations
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must be avoided. */
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_dl_relocate_static_pie ();
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/* Perform IREL{,A} relocations. */
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ARCH_SETUP_IREL ();
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/* The stack guard goes into the TCB, so initialize it early. */
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ARCH_SETUP_TLS ();
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/* In some architectures, IREL{,A} relocations happen after TLS setup in
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order to let IFUNC resolvers benefit from TCB information, e.g. powerpc's
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hwcap and platform fields available in the TCB. */
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ARCH_APPLY_IREL ();
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/* Set up the stack checker's canary. */
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uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
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# ifdef THREAD_SET_STACK_GUARD
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THREAD_SET_STACK_GUARD (stack_chk_guard);
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# else
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__stack_chk_guard = stack_chk_guard;
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# endif
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# ifdef DL_SYSDEP_OSCHECK
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{
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/* This needs to run to initiliaze _dl_osversion before TLS
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setup might check it. */
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DL_SYSDEP_OSCHECK (__libc_fatal);
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}
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# endif
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/* Initialize libpthread if linked in. */
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if (__pthread_initialize_minimal != NULL)
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__pthread_initialize_minimal ();
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/* Set up the pointer guard value. */
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uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
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stack_chk_guard);
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# ifdef THREAD_SET_POINTER_GUARD
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THREAD_SET_POINTER_GUARD (pointer_chk_guard);
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# else
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__pointer_chk_guard_local = pointer_chk_guard;
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# endif
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#endif /* !SHARED */
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/* Register the destructor of the dynamic linker if there is any. */
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if (__glibc_likely (rtld_fini != NULL))
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__cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL);
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#ifndef SHARED
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/* Perform early initialization. In the shared case, this function
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is called from the dynamic loader as early as possible. */
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__libc_early_init (true);
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/* Call the initializer of the libc. This is only needed here if we
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are compiling for the static library in which case we haven't
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run the constructors in `_dl_start_user'. */
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__libc_init_first (argc, argv, __environ);
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/* Register the destructor of the statically-linked program. */
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__cxa_atexit (call_fini, NULL, NULL);
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/* Some security at this point. Prevent starting a SUID binary where
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the standard file descriptors are not opened. We have to do this
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only for statically linked applications since otherwise the dynamic
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loader did the work already. */
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if (__builtin_expect (__libc_enable_secure, 0))
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__libc_check_standard_fds ();
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#endif /* !SHARED */
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/* Call the initializer of the program, if any. */
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#ifdef SHARED
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if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
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GLRO(dl_debug_printf) ("\ninitialize program: %s\n\n", argv[0]);
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if (init != NULL)
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/* This is a legacy program which supplied its own init
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routine. */
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(*init) (argc, argv, __environ MAIN_AUXVEC_PARAM);
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else
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/* This is a current program. Use the dynamic segment to find
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constructors. */
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call_init (argc, argv, __environ);
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/* Auditing checkpoint: we have a new object. */
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_dl_audit_preinit (GL(dl_ns)[LM_ID_BASE]._ns_loaded);
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
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GLRO(dl_debug_printf) ("\ntransferring control: %s\n\n", argv[0]);
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#else /* !SHARED */
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call_init (argc, argv, __environ);
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_dl_debug_initialize (0, LM_ID_BASE);
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#endif
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__libc_start_call_main (main, argc, argv MAIN_AUXVEC_PARAM);
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}
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/* Starting with glibc 2.34, the init parameter is always NULL. Older
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libcs are not prepared to handle that. The macro
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DEFINE_LIBC_START_MAIN_VERSION creates GLIBC_2.34 alias, so that
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newly linked binaries reflect that dependency. The macros below
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expect that the exported function is called
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__libc_start_main_impl. */
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#ifdef SHARED
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# define DEFINE_LIBC_START_MAIN_VERSION \
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DEFINE_LIBC_START_MAIN_VERSION_1 \
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strong_alias (__libc_start_main_impl, __libc_start_main_alias_2) \
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versioned_symbol (libc, __libc_start_main_alias_2, __libc_start_main, \
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GLIBC_2_34);
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# if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_34)
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# define DEFINE_LIBC_START_MAIN_VERSION_1 \
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strong_alias (__libc_start_main_impl, __libc_start_main_alias_1) \
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compat_symbol (libc, __libc_start_main_alias_1, __libc_start_main, GLIBC_2_0);
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# else
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# define DEFINE_LIBC_START_MAIN_VERSION_1
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# endif
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#else /* !SHARED */
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/* Enable calling the function under its exported name. */
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# define DEFINE_LIBC_START_MAIN_VERSION \
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strong_alias (__libc_start_main_impl, __libc_start_main)
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#endif
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/* Only define the version information if LIBC_START_MAIN was not set.
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If there is a wrapper file, it must expand
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DEFINE_LIBC_START_MAIN_VERSION on its own. */
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#if DO_DEFINE_LIBC_START_MAIN_VERSION
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DEFINE_LIBC_START_MAIN_VERSION
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#endif
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